Positioning tag with alert function

ABSTRACT

A mobile data processing device configured to assist in locating a user. The device comprises an enclosure and an attachment base for attaching the device to a garment, lanyard or strap wearable by a user. The attachment base moves between a first (“normal”) position and a second (“alert”) position with respect to the enclosure in response to an external force acting on the enclosure. The device further comprises a detector system for detecting removal of the attachment base from the normal position, and an alert signal generator configured to send an alert signal in response to said detection. The alert signal can be generated quickly by grabbing the enclosure and pulling the device downwards.

FIELD OF THE INVENTION

The present invention relates generally to techniques for positioning aportable device and generating an alert signal in case of distress oremergency.

BACKGROUND OF THE INVENTION

Smartphones typically include GPS (Global Positioning System) circuitry.The GPS circuitry of modern smartphones may be sufficiently sensitive todetermine the smartphone's location inside buildings. Unfortunately theaccuracy of GPS inside buildings is poor. This is because GPSpositioning is based on travel time differences from a number ofsatellites, and when all the satellites are received through the samewindow, the travel time differences are the same regardless of thesmartphone's position within the building.

In order to track the location of persons in places where GPSpositioning is insufficient, it is customary to use positioning devicesthat is based on signals whose one or more parameters depend from theposition of the device in a known or predictable manner. For instance,such positioning may be based on radio signal strength or qualityobservations. In some implementations a positioning device observessignal parameters, such as strength or quality, from various radiobeacons, such as WLAN (wireless local-area network) access points ordedicated positioning transmitters. These observations are then used,either in the device itself or in an external positioning engine, todetermine the device's position. In other implementations the scheme isreversed and the fixed stations observe a signal transmitted by thedevice to be positioned. Alternatively or additionally, signal contentmay be used. For instance, detection of a specific transmitter's carriersignal is in itself a useful indicator of position, regardless of thestrength or quality of that signal. Detection of a transmitter'sidentity may be sufficient for positioning the device in cases whereinthe transmitter's signal cannot propagate through walls. Visible light,infrared radiation, microwave radiation and ultrasound are examples ofsignals that are practically confined to the spaces in which they aretransmitted, and serve as indicators of the device's presence in therespective spaces.

It is customary to use the term “tag” or “positioning tag” to mean apositioning device whose sole or primary purpose is to keep track of aperson or object the tag is attached to. Such positioning techniques andtags are well known in the art and can be obtained from a number ofsources, including the assignee of the invention described later in thisdocument.

A residual problem in existing positioning tags relates to generation ofan alert signal in case of distress or emergency. For instance,commonly-owned PCT application WO2009/122000 describes, in connectionwith FIG. 9, a positioning tag with a push button for triggering analert condition. In the prior art systems, the wearer of the positioningtag needs time to find the alert button. If the person is usingprotective gloves or mittens, it may be impossible to press a smallbutton.

SUMMARY OF THE INVENTION

It is an object of the present invention to alleviate at least oneproblem relating to generation of an alert signal from a positioning tagin case of distress or emergency.

In one implementation the invention is a mobile data processing device,which comprises an enclosure and a power source; a memory system forstoring program instructions; a processing system for executing theprogram instructions; a transmission system for communicating with atleast one communication system, wherein the at least one communicationsystem comprises or cooperates with a positioning system for positioningthe mobile data processing device. The functionality listed in thepreceding sentence is well known in the art, and illustrative referencedocuments are listed at the end of this description.

In order to improve alert signal generation, the transmission system isconfigured to send at least one alert signal in response to fulfillmentof a first set of predetermined alert conditions. The first set of alertconditions may optionally include pressing a button. But finding abutton in an emergency may take time. To alleviate this problem, themobile data processing device comprises an attachment base for attachingthe mobile data processing device to a garment, lanyard or strap that iswearable by a user. The attachment base is configured to move between afirst position (normal position) and a second position (alert position)with respect to the enclosure in response to an external force. Theexternal force is conveniently exerted by pulling the enclosure againstthe attachment base, which is attached to the user's clothing, belt orlanyard. When the mobile data processing device is suspended from theattachment base, a force exceeding a threshold and pulling the enclosuredownwards moves the attachment base to the second position with respectto the enclosure. The mobile data processing device also comprises adetector system for detecting presence of the attachment base in thesecond position (alert position). The mobile data processing devicefurther comprises an alert signal generator having an input coupled tothe detector system and an output coupled to the transmission system,wherein the alert signal generator is configured to cause transmissionof at least one alert signal in response to a detected presence of theattachment base in the second position.

In some implementations the mobile data processing device comprising areception system for receiving messages and, optionally, a displaysystem for displaying the received messages.

To maximize battery life the mobile data processing device may comprisea sleep mode circuitry for putting the mobile data processing device toa power save mode in response to fulfillment of a second set ofpredetermined conditions, such as passage of time since last detectedactivity, lack of user motion, and/or activation of a sleep mode userinterface element, eg a button. If the mobile data processing devicecomprises the sleep mode circuitry, it should also comprise a wake-upcircuitry for putting the mobile data processing device to active modein response to fulfillment of a third set of predetermined conditions,such as periodically and/or in response to detection of user motion. Thesleep mode circuitry, if implemented, is configured to control power tothe reception system, wherein after sending the at least one alertsignal, the sleep mode circuitry keeps the reception system powereduntil an acknowledgement to the at least one alert signal is received.

In some implementations the mobile data processing device with theattachment base in the first (normal) position is visually differentfrom the mobile data processing device with the attachment base in thesecond (alert) position.

In order to ensure that users with relatively small hands can grab theenclosure and pull it against the attachment base, the enclosure, whensuspended from the attachment base, should have a horizontal width ofnot more than 10 cm. In order to secure a good grip, the enclosure, whensuspended from the attachment base, has a horizontal width of not lessthan 4 cm.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following section, specific embodiments of the invention will bedescribed in greater detail in connection with illustrative butnon-restrictive examples. A reference is made to the following drawings:

FIG. 1A presents an overview of a positioning tag with an alertfunction;

FIG. 1B shows the positioning tag in an alert condition;

FIG. 2 shows a schematic block diagram of a mobile data processingdevice configured to act as a positioning tag with an alert function;

FIGS. 3A and 3B illustrate one specific implementation for detectingmovement of the attachment base into the alert position; and

FIGS. 4A and 4B illustrate another illustrative implementation fordetecting movement of the attachment base into the alert position;

FIG. 5 illustrates a residual problem relating to forces acting on thepositioning tag;

FIG. 6 illustrates exemplary optional features directed to solving theforce-related problems discussed in connection with FIG. 5; and

FIGS. 7A, 7B and 7C illustrate successive states of a positioning tagaccording to an embodiment, with an increasing force F acting on theattachment base.

DETAILED DESCRIPTION OF SOME SPECIFIC EMBODIMENTS

FIG. 1A presents an overview of a positioning tag 100 with an alertfunction. The positioning tag 100 has an enclosure 102. The enclosurecontains the normal elements of a positioning tag, as explained in moredetail in the prior art. The normal elements include electroniccircuitry, which will be described in more detail in connection withFIG. 2, and user interface elements, which in the present exampleinclude a display 120 and keypad 130.

For the purposes of the present invention, the positioning tag 100comprises an attachment base 104, which has a formation 106 forattachment to the user. In the present example, the formation 106 is ahole and the attachment to the user or the user's clothing takes placeby means of a lanyard 108. In a typical use case, the positioning tagmay be suspended form the lanyard which is carried around the user'sneck. Alternatively the attachment base 104 and the formation 106 may beattached to a hook or shackle supported by the user's belt. In yetfurther implementations the formation 106 may comprise a hook or shacklewhich is clipped to a lanyard, buttonhole or belt of the user.

In FIG. 1A the positioning tag is shown in a normal position, in acondition wherein the user has remained motionless for a time which isdeemed sufficient to place the positioning tag in a sleep or power downmode. In the sleep mode, non-critical functions are powered down, whichis indicated herein by the fact that the display is shut off. Theattachment base 104 is in a first position, which is it's normalposition.

FIG. 1B shows the positioning tag in an alert condition. The positioningtag has been pulled against the lanyard 108 (or other means ofattachment) with a sufficient force to move the attachment base 104 to asecond position with respect to the enclosure 102. The second positionis called alert position. The electronic circuitry, which will bedescribed in more detail later, detects the movement of the attachmentbase 104 to the alert position and responds by ensuring that thepositioning tag is powered up and by sending an alert signal.

FIG. 2 shows a schematic block diagram of a mobile data processingdevice configured to act as a positioning tag with an alert function.The positioning tag, denoted by reference sign PT, comprises aprocessing system 202 with at least one central processing unit. Thepositioning tag further comprises a memory system 250, which typicallycomprises a combination of fast volatile memory and slower non-volatilememory, as is well known to those skilled in the art. In addition, thepositioning tag PT may comprise or utilize a user interface 210, whichcomprises an input circuitry 212 and an output circuitry 214. The inputcircuitry 212 comprises the positioning tag's user-input devices, suchas a keypad. The output circuitry 214 comprises the positioning tag'saudio and/or visual output devices, such as a text display, lightindicator(s) and/or sound output device(s). The positioning tag PTfurther comprises reception/transmission circuitry 220 which comprises atransmission circuitry 222, reception circuitry 224 and antenna 226 forat least one communication technology. A typical example of anappropriate communication technology is WLAN (Wireless Local AreaNetwork). A WLAN network is a typical but non-restrictive example ofaccess networks AN which support wireless mobility of the positioningtags. The access network AN is typically coupled via a data network,such as a LAN (Local Area Network) to a positioning engine PE and amonitoring terminal MT. The reception/transmission circuitry 220typically contains signal strength or quality sensors, such as an RSSI(received signal strength indicator) sensor. In some implementations theobservations of the RSSI sensor are utilized to determine the locationof the positioning tag.

The positioning tag's memory 250 comprises routines for controlling theoperations of the processing system 202 which, in turn, controls theoperations of the entire positioning tag. FIG. 2 shows an arrangement inwhich the memory 250 of the positioning tag stores apps (applications)260 for execution by the central processing unit CP. Reference numeral280 denotes an area of the memory 250 used to store parameters andtemporary variables.

In addition to the user interface 210, the positioning tag comprisesvarious sensors, collectively denoted by reference number 240. For thepurposes of the present invention, one of the sensors is an alert sensorthat detects the placement of the attachment base 104 in the secondposition that corresponds to the alert condition. The sensor assembly240 may comprise optional sensors for detecting environmental variablesor parameters. A non-exhaustive list of sensors 240 includes IR(infrared) detection/communication circuitry, GPS and/or otherlocation-determination circuitry, RFID (radio frequency identification)and/or NFC (near-field communication) circuitry, or the like, by meansof which location determination of the positioning tag can beaccomplished or enhanced.

The enclosure naturally comprises a power supply (not shown separately),such as a battery. In order to minimize energy consumption and maximizebattery life, the positioning tag may comprise sleep mode circuitry,which puts the positioning tag to a power save mode when it encounters apredetermined set of conditions. In the power save mode, non-criticalfunctions are powered down, such as the display and communicationsfunctions.

The sensor assembly 240 typically comprises a motion sensor, which isused in combination with a set of timers. In a typical implementation,the power save mode is entered when the positioning tag has remainedmotionless for a period of time. In the present context, motionlessmeans that the user's movement, and that of the positioning tag, issystematic and exceeds slight variations in sitting position. In atypical implementation, the positioning tag also has wake-up circuitryto take the positioning tag out of the power save mode on detection ofanother predetermined set of conditions. In a typical implementation,the power save mode is terminated on detection of movement exceedingslight variations in sitting position and/or periodically, whereby thepositioning engine may confirm that the positioning tag remainsfunctional even if it is not in motion.

One function that should not be powered off is naturally the alertfunction. Even if much of the positioning tag is in the power save mode,the alert detection should remain active and able to bring thepositioning tag to full functionality. Also, when the alert conditionhas been detected and the alert signal has been transmitted, thecommunications functions should be kept active until an acknowledgementis received and displayed on the positioning tag's display or otherindicator.

FIGS. 3A and 3B illustrate one specific implementation for detectingmovement of the attachment base into the alert position. FIG. 3A showsthe attachment base 104 in the normal position and FIG. 3B in the alertposition. In the present illustrative example, the attachment base 104has formation 310, against which an external force is exerted, in thisexample by a tip or wheel 308, which is pushed against the attachmentbase 104 by a shaft 304 and spring 302. In the present example, theformation 310 in the attachment base 104 is shaped in such a manner thatthe spring 302 has two energy minima, one corresponding to the normalposition and the other to the alert position. A benefit of thisarrangement is that the energy minima resist pulling of the attachmentbase towards the alert position by a force which is sufficient forpreventing accidental alerts.

In order to detect movement of the attachment base into the alertposition, the present implementation comprises a switch 316 which isguided by a second formation 312 of the attachment base 104. In theimplementation shown in FIGS. 3A and 3B, the switch 316 is of a normallyclosed (NC) type, and it is held in the open (non-connecting) state bythe formation 312 of the attachment base 104. In the alert positionshown in FIG. 3B the formation 312 no longer prevents the switch 316from closing. Closure of the switch 316 is detected by the electroniccircuitry, which responds by ensuring that the positioning tag ispowered up and by sending an alert signal. A benefit of using an NC-typeswitch is that complete detachment of the attachment base 104 from theenclosure 102 results in continuous detection of the alert condition.The attachment base preferably resists complete detachment from theenclosure by a force which is sufficient to prevent accidental breakingof the positioning tag, yet not strong enough to allow serious injury tothe user in cases where the positioning tag is accidentally caught in anobstacle, or an attacker grabs it. In the examples shown in FIGS. 3A and3B, when an overly strong force pulls the attachment base away from theenclosure, either the tip or wheel 308 breaks or the formation 310 inthe attachment breaks. In either case the attachment base detacheswithout serious injury to the user.

FIGS. 4A and 4B show another illustrative example. In this example, theattachment base 104 extends across the enclosure 102 and does not slide“out of” and “into” the enclosure 102. Similarly to the previousexample, an NC switch 316 is kept in an open (non-alert) state by aformation 312 in the attachment base. The attachment base 104 is kept inthe first (normal) position by one or more springs 302. In the situationshown in FIG. 4B the enclosure 102 is pulled against the attachment base104 by a force sufficient for the spring(s) 302 to compress such thatthe switch 316 closes and triggers the alert.

FIG. 5 illustrates a residual problem relating to forces acting on thepositioning device. In the scenario shown in FIG. 5 the positioning tag100 lies against an obstacle 502, such a rail of a hospital bed. A partof the user's weight imposes a force W on the enclosure 102 against therelatively sharp rail 502. The user, who may be assisting a patient,raises their head, which imposes a pulling force P on the attachmentbase 104 via the lanyard 108. This is a representative example ofsituations which have caused breakages and/or false alarms in prior artpositioning tags. For instance, if the force P has a component thattends to pull the attachment base 104 towards the alert position, afalse alert may be triggered although the user may not be aware of thegenerated alert signal. And if the force P has a component perpendicularto the face (largest surface) of the enclosure 102, the force P tends topull the front and rear halves of the enclosure apart from each other.Or, the force P may result in misalignment of the switch 312 and theformation 316 that presses against the switch, which may also causefalse alarms.

The inventors have discovered that it is beneficial to dimension thestructural elements (wall thicknesses, material rigidity, jointstrengths) in such a manner that the positioning tag 100 withstands,without breaking or detecting removal of the attachment base from thefirst position, a force P of at least 150N, wherein the force P acts onthe attachment base 104, in parallel with the normal of the face (thelargest surface) of the positioning tag, when a correspondingcounterforce W acts on the face of the positioning tag. Experience hasshown that the counterforce W is usually fairly evenly-distributed, asit is typically caused by the user's weight.

FIG. 6 illustrates exemplary optional features directed to solving theforce-related problems discussed in connection with FIG. 5. In order toalleviate or eliminate the problems discussed in connection with FIG. 5,the embodiment shown in FIG. 6 contains some improvements over theprevious embodiments. For instance, the front and rear halves of theenclosure, denoted here by reference number 602, are very stronglyjoined with each other. The hatched areas in the enclosure 602, indicateareas in which the front and rear halves are joined with each other.Applicable techniques include ultrasonic welding, gluing, screwing,riveting and combinations thereof, to name just a few examples.Ultrasonic welding and gluing are very effective techniques, becauselarge areas contribute to sharing the loads.

As stated in connection with FIG. 5, one of the residual problems inprior art positioning tags was the possibility to trigger false alertsin situations where a force P accidentally acted on the attachment base104. In order to further reduce the risk of false alerts, the embodimentshown in FIG. 6 is constructed in such a manner that generation ofalerts, be they triggered on purposed or by accident, causes a clearvisual change in the appearance of the positioning tag. In the presentembodiment the attachment base has an energy maximum (a peak) betweenthe first (normal) and second (alert) positions, and the alert detectionsystem is dimensioned in such a manner that the alert condition isdetected only after the attachment base has moved from the normalposition beyond the energy maximum towards the alert position. Becausethe attachment base 104 has to proceed beyond the energy maximum towardsan energy minimum (at least a local one), it is simply impossible forthe attachment base to move to a position in which a false alert isgenerated and then spontaneously to return to the normal position,without any visual indication of the alert condition to the user.

In the present embodiment this scheme is implemented as follows.Reference number 620 denotes a formation in the enclosure, whichsimultaneously contributes to two aspects by which the number of falsealerts can be reduced. Firstly, the attachment base 104 has at least one(two are shown) spring-loaded tips 610, which press against theformation 620. The formation 620 has two troughs 622 and 626, such thatthe presence of the spring-loaded tip(s) 610 in the first trough 622corresponds to the normal position, and the presence of thespring-loaded tip(s) 610 in the second trough 624 corresponds to thealert position. The two troughs 622, 626 constitute local energy minimafor the spring-loaded tip(s) 610. Between the troughs there is a peak624, which constitutes a local energy maximum for each tip 610.Secondly, the formation 620 contributes to joining of the front and rearhalves of the enclosure 102 close the attachment base 104, that is,exactly where strength against distorting forces are needed.

In the present embodiment, the attachment base 104 presses against amicro switch 660, which acts as the primary alert-detection sensor, bymeans of an elongated shaft 630 through the formation 620. The microswitch 660 is located on an circuit board 650, while the attachment base104 is on the opposite side of the formation, as seen from the circuitboard. An implementation wherein the elongated shaft 630 penetrates theformation 620 to act on the micro switch 660 has the benefit that allelectronic components, including the micro switch 660, can be installedon the circuit board 650, and yet the formation 620 that separates thecircuit board from the attachment base can contribute to the strength ofthe enclosure.

An obvious way to influence a sensor located on the circuit board is touse a Hall-effect sensor on the circuit board and a magnet in theattachment base. The inventors have discovered, however, thatHall-effect sensors can be influenced by external magnets, such asmagnets of neighboring positioning tags when the tags are stacked on topof one another. In other words, false alerts could result from briningmultiple tags too close to each other.

FIGS. 7A, 7B and 7C illustrate successive states of a tag according toan embodiment, with an increasing force F acting on the attachment base104. In this embodiment, the attachment base 104 connects to the lanyard108 (see FIGS. 1A, 1B) via a clip or shackle 710. The clip 710 has alatch 712 which is configured to open when a force F exceeds a giventhreshold, wherein the force F pulls the attachment base 104 away fromthe enclosure 102 of the tag. FIG. 7A shows a normal state in which thetag hangs freely from the clip 710 and lanyard (omitted here forclarity). When the force F exceeds a first threshold force F₁, theattachment base 104 moves with respect to the enclosure 102. This stateis shown in FIG. 7B. The tag detects the movement which indicates analert condition, and sends an alert signal. When the force F is furtherincreased beyond a second threshold force F₂, which is higher than thefirst threshold force F₁, the latch 712 opens and the entire tag isdetached from the lanyard. This state is shown in FIG. 7C. A benefit ofthis feature is reduced risk of physical harm to the user in case ofattacks on the user.

In the embodiments shown in the drawings, the first force thresholdwhich must be exceeded to generate an alert signal, is caused by thespring(s) 302 in FIGS. 3A, 3B, 4A and 4B. Those skilled in the art willrealized that helical springs are graphical symbols for elasticelements, but the threshold F₁ can be attained by a variety ofalternative implementations. For instance, other forms of springs,besides helical springs, can be used. Instead of springs, blocks ofelastic material can be used. As a yet further alternative, theattachment based 104 may be drawn towards its normal position by magnets(not shown), whose separation from one another requires a force Fexceeding the first force threshold F₁.

In FIGS. 7A, 7B and 7C, the latch 712 is shown as a feature of aseparate clip, but it is possible to integrate the latch with theattachment base. Alternatively, the tag, and particularly the connectionof the attachment base and the enclosure, can be dimensioned in such amanner that the attachment base is entirely detached from the enclosurewhen the second threshold force F₂ is exceeded.

The preceding discussion relates to a force F acting to detach theattachment base 104 from the enclosure 102. According to a furtherbeneficial feature, the attachment base 104 and enclosure 102 comprise amotion stopper, depicted by reference number 720, which resists pushingthe attachment base 104 towards its normal (non-alert) position andbeyond. In the implementation shown in FIG. 7B, the motion stopper 720comprises a butt joint between the attachment base 104 and enclosure102.

The inventors have discovered that the first force threshold F₁, whichmust be exceeded to detect the alert condition and trigger the alertsignal, is preferably about 15-35N, and optimally about 24N, to preventfalse alerts.

The second threshold force F₂, which must be exceeded to completelydetach the tag from the lanyard or other support, should be higher thanthe first force threshold F₁, preferably about 40-60N and optimallyabout 50N. This dimensioning ensures that the alert condition isdetected before the tag is detached from the lanyard or other support.

The second threshold force F₂ should also be less than 120N, preferablyabout 60-100N and optimally about 80N, to avoid injury to the personnelin case of attack.

The enclosure and attachment base should be dimensioned to withstand allof the above forces, that is, any forces up to the one by which the tagis detached from the lanyard or other support.

Finally, the enclosure and attachment base should be dimensioned towithstand a force of about 100N, which pushes the attachment basetowards its normal position. This feature reduces the risk of damage tothe mechanism and/or the detector (item 316 in FIGS. 3A, 3B, 4A and 4B),if excessive force is used to push the attachment base to the normalposition.

Those skilled in the art will realize that the inventive principle maybe modified in various ways without departing from the spirit and scopeof the present invention.

COMMONLY-OWNED PATENT APPLICATIONS

-   -   WO2009/122000A1    -   WO2011/058228A1        These are illustrative but non-exhaustive examples of documents        describing positioning functionality of positioning tags.

We claim:
 1. A mobile data processing device, comprising: an enclosureand a power source; a memory system for storing program instructions; aprocessing system for executing the program instructions; a transmissionsystem for communicating with at least one communication system, whereinthe at least one communication system comprises or cooperates with apositioning system for positioning the mobile data processing device;wherein the transmission system is configured to send at least one alertsignal in response to fulfillment of a first set of predetermined alertconditions; an attachment base for attaching the mobile data processingdevice to a garment, lanyard or strap that is wearable by a user;wherein the attachment base is configured to move between a firstposition and a second position with respect to the enclosure in responseto an external force, wherein when the mobile data processing device issuspended from the attachment base, a force exceeding a threshold andpulling the enclosure downwards moves the attachment base to the secondposition with respect to the enclosure; a detector system for detectingremoval of the attachment base from the first position; an alert signalgenerator having an input coupled to the detector system and an outputcoupled to the transmission system, wherein the alert signal generatoris configured to cause transmission of at least one alert signal inresponse to a detected removal of the attachment base from the firstposition.
 2. The mobile data processing device according to claim 1,further comprising a reception system for receiving messages.
 3. Themobile data processing device according to claim 2, further comprising adisplay system for displaying the received messages.
 4. The mobile dataprocessing device according to claim 1, further comprising a sleep modecircuitry for putting the mobile data processing device to a power savemode in response to fulfillment of a second set of predeterminedconditions.
 5. The mobile data processing device according to claim 4,further comprising a wake-up circuitry for putting the mobile dataprocessing device to active mode in response to fulfillment of a thirdset of predetermined conditions.
 6. The mobile data processing deviceaccording to claim 4, wherein the sleep mode circuitry is configured tocontrol power to the reception system, wherein after sending the atleast one alert signal, the sleep mode circuitry keeps the receptionsystem powered until an acknowledgement to the at least one alert signalis received.
 7. The mobile data processing device according to claim 1,wherein the mobile data processing device with the attachment base inthe second position is visually different from the mobile dataprocessing device with the attachment base in the first position.
 8. Themobile data processing device according to claim 7, wherein the firstposition and the second position constitute local energy minima for theattachment base, and there is at least one local energy maximum betweenthe first position and the second position.
 9. The mobile dataprocessing device according to claim 8, wherein the detector system doesnot detect said removal of the attachment base from the first positionbefore the attachment base has proceeded beyond the local energymaximum.
 10. The mobile data processing device according to claim 1,wherein the enclosure, when suspended from the attachment base, has ahorizontal width of not more than 10 cm.
 11. The mobile data processingdevice according to claim 1, wherein the enclosure, when suspended fromthe attachment base, has a horizontal width of not less than 4 cm. 12.The mobile data processing device according to claim 1, wherein themobile data processing device is configured to resist pulling of theattachment base from the first position to the second position by afirst force which is about 15-35N.
 13. The mobile data processing deviceaccording to claim 12, wherein the first force is about 20-28N.
 14. Themobile data processing device according to claim 12, wherein the mobiledata processing device is configured to resist detachment of theattachment base from the enclosure by a second force which is greaterthan the first force and about 40-60N.
 15. The mobile data processingdevice according to claim 14, wherein the second force is about SON. 16.The mobile data processing device according to claim 1, furthercomprising structural elements dimensioned in such a manner that themobile data processing device withstands, without breaking or detectingremoval of the attachment base from the first position, a force of atleast 150N acting on the attachment base and in parallel with a normalof a largest surface of the enclosure, against a correspondingcounterforce acting on the largest surface of the enclosure.